Power semiconductor module and power conversion apparatus

ABSTRACT

A power semiconductor module includes an insulating substrate, a first conductive circuit pattern, a second conductive circuit pattern, a first semiconductor device, a second semiconductor device, a sealing member, and a first barrier layer. The sealing member seals the first semiconductor device, the second semiconductor device, the first conductive circuit pattern, and the second conductive circuit pattern. At least one of the first barrier layer and the sealing member includes a first stress relaxation portion. This configuration improves the reliability of the power semiconductor module.

TECHNICAL FIELD

The present invention relates to a power semiconductor module and apower conversion apparatus.

BACKGROUND ART

WO 2014/128899 (PTL 1) discloses semiconductor equipment including aplurality of semiconductor devices, a substrate having the plurality ofsemiconductor devices mounted thereon, and resin sealing the substrateand the plurality of semiconductor devices. The semiconductor devicesand the substrate are partially covered with a glass film that containsvanadium and tellurium. The glass film prevents or reduces moisture frompenetrating to the semiconductor devices and other components.

CITATION LIST Patent Literature

PTL 1: WO 2014/128899

SUMMARY OF INVENTION Technical Problem

However, while in operation or under an ambient temperature change, thesemiconductor equipment disclosed in PTL 1 warps. This causes stress onthe glass film, causing cracks in the glass film. The cracks in theglass film let moisture and gas through, decreasing the reliability ofthe semiconductor equipment. The present invention has been made in viewof the above problem. An object of the present invention is to provide apower semiconductor module and a power conversion apparatus havingimproved reliability.

Solution to Problem

A power semiconductor module of the present invention includes aninsulating substrate, a first conductive circuit pattern, a secondconductive circuit pattern, a first semiconductor device, a secondsemiconductor device, a sealing member, and a first barrier layer. Theinsulating substrate includes a first main face. The first conductivecircuit pattern is provided on the first main face. The secondconductive circuit pattern is provided on the first main face. Thesecond conductive circuit pattern is separated from the first conductivecircuit pattern by a first gap. The first semiconductor device is joinedto the first conductive circuit pattern. The second semiconductor deviceis joined to the second conductive circuit pattern. The sealing memberseals the first semiconductor device, the second semiconductor device,the first conductive circuit pattern, and the second conductive circuitpattern. The first barrier layer is disposed on the opposite side fromthe insulating substrate with respect to the first semiconductor deviceand the second semiconductor device. The first barrier layer is providedon or in the sealing member. At least one of the first barrier layer andthe sealing member includes a first stress relaxation portion.

A power conversion apparatus of the present invention includes a mainconversion circuit and a control circuit. The main conversion circuitincludes a power semiconductor module of the present invention and isconfigured to convert input power and output the converted power. Thecontrol circuit is configured to output a control signal to the mainconversion circuit for controlling the main conversion circuit.

Advantageous Effects of Invention

In the power semiconductor module and the power conversion apparatus ofthe present invention, the first barrier layer prevents or reducesmoisture and gas from penetrating to the first semiconductor device, thesecond semiconductor device, the first conductive circuit pattern, thesecond conductive circuit pattern, and the insulating substrate. Thefirst stress relaxation portion reduces stress on the first barrierlayer caused by the warp of the power semiconductor module, and preventsthe first barrier layer from cracking. The power semiconductor module ofthe present invention has improved reliability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of a power semiconductor moduleaccording to embodiment 1.

FIG. 2 is an enlarged schematic partial cross-sectional view of thepower semiconductor module according to embodiment 1, taken alongsection line II-II in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a power semiconductormodule according to a first variation of embodiment 1.

FIG. 4 is a schematic cross-sectional view of a power semiconductormodule according to a second variation of embodiment 1.

FIG. 5 is a schematic cross-sectional view of a power semiconductormodule according to a third variation of embodiment 1.

FIG. 6 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 2.

FIG. 7 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 3.

FIG. 8 is a schematic cross-sectional view of a power semiconductormodule according to a variation of embodiment 3.

FIG. 9 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 4.

FIG. 10 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 5.

FIG. 11 is a schematic cross-sectional view of a power semiconductormodule according to a variation of embodiment 5.

FIG. 12 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 6.

FIG. 13 is a schematic plan view of a power semiconductor moduleaccording to embodiment 7.

FIG. 14 is a schematic cross-sectional view of the power semiconductormodule according to embodiment 7, taken along section line XIV-XIV inFIG. 13.

FIG. 15 is a schematic cross-sectional view of a power semiconductormodule according to a first variation of embodiment 7.

FIG. 16 is a schematic cross-sectional view of a power semiconductormodule according to a second variation of embodiment 7.

FIG. 17 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 8.

FIG. 18 is a schematic cross-sectional view of a power semiconductormodule according to embodiment 9.

FIG. 19 is a block diagram showing a configuration of a power conversionsystem according to embodiment 10.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will now be described. Like partsare designated by like reference signs, and the description of suchparts is not repeated.

Embodiment 1

With reference to FIGS. 1 and 2, a power semiconductor module 1 inembodiment 1 will now be described. Power semiconductor module 1 mainlyincludes an insulating substrate 11, a first conductive circuit pattern13, a second conductive circuit pattern 14, a first semiconductor device20, a second semiconductor device 21, a sealing member 40, and a firstbarrier layer 50. Power semiconductor module 1 may further include acase 30. Power semiconductor module 1 may further include a thirdconductive circuit pattern 13 b, a fourth conductive circuit pattern 14b, a third semiconductor device 20 b, and a fourth semiconductor device21 b.

Insulating substrate 11 extends in a first direction (x-direction) andin a second direction (y-direction) perpendicular to the firstdirection. Insulating substrate 11 includes a first main face 11 m and asecond main face 11 n opposite to first main face 11 m. Insulatingsubstrate 11 may include a first insulating substrate segment 11 a and asecond insulating substrate segment 11 b. Second insulating substratesegment 11 b is separated from first insulating substrate segment 11 aby a second gap 12 in the first direction (x-direction). Second gap 12may be located in the central portion of power semiconductor module 1 inthe first direction (x-direction). As used herein, the central portionof the power semiconductor module in the first direction (x-direction)refers to the middle portion of the three portions when the powersemiconductor module is trisected along the first direction(x-direction).

Insulating substrate 11 may further include a third insulating substratesegment 11 c and a fourth insulating substrate segment 11 d. Thirdinsulating substrate segment 11 c is separated from first insulatingsubstrate segment 11 a by a gap in the second direction (y-direction).The gap between first insulating substrate segment 11 a and thirdinsulating substrate segment 11 c may be located in the central portionof power semiconductor module 1 in the second direction (y-direction).As used herein, the central portion of the power semiconductor module inthe second direction (y-direction) refers to the middle portion of thethree portions when the power semiconductor module is trisected alongthe second direction (y-direction).

Fourth insulating substrate segment 11 d is separated from secondinsulating substrate segment 11 b by a gap in the second direction(y-direction). The gap between second insulating substrate segment 11 band fourth insulating substrate segment 11 d may be located in thecentral portion of power semiconductor module 1 in the second direction(y-direction). Fourth insulating substrate segment 11 d is separatedfrom third insulating substrate segment 11 c by a gap in the firstdirection (x-direction). The gap between third insulating substratesegment 11 c and fourth insulating substrate segment 11 d may be locatedin the central portion of power semiconductor module 1 in the firstdirection (x-direction).

Insulating substrate 11 may be composed of, but is not limited to, aninorganic ceramic material, such as alumina (Al₂O₃), aluminum nitride(AlN), silicon nitride (Si₃N₄), silicon dioxide (SiO₂), or boron nitride(BN). Insulating substrate 11 may be composed of a resin material withat least one of fine grain and filler dispersed. The at least one offine grain and filler may be composed of an inorganic ceramic material,such as alumina (Al₂O₃), aluminum nitride (AlN), silicon nitride(Si₃N₄), silicon dioxide (SiO₂), boron nitride (BN), diamond (C),silicon carbide (SiC), or boron oxide (B₂O₃); or may be composed of aresin material, such as silicone resin or acrylic resin. The resin withat least one of fine grain and filler dispersed has electricalinsulation properties. The resin with at least one of fine grain andfiller dispersed may be composed of, but is not limited to, epoxy resin,polyimide resin, silicone resin, or acrylic resin.

First conductive circuit pattern 13 is provided on first main face 11 m.In particular, first conductive circuit pattern 13 may be provided onfirst insulating substrate segment 11 a. Second conductive circuitpattern 14 is provided on first main face 11 m. Second conductivecircuit pattern 14 is separated from first conductive circuit pattern 13by a first gap 17 in the first direction (x-direction). First gap 17 maybe located in the central portion of power semiconductor module 1 in thefirst direction (x-direction). In particular, second conductive circuitpattern 14 may be provided on second insulating substrate segment 11 b.Each of first conductive circuit pattern 13 and second conductivecircuit pattern 14 may be composed of, but is not limited to, a metalmaterial, such as copper or aluminum.

Third conductive circuit pattern 13 b is provided on first main face 11m. In particular, third conductive circuit pattern 13 b may be providedon third insulating substrate segment 11 c. Third conductive circuitpattern 13 b is separated from first conductive circuit pattern 13 by agap in the second direction (y-direction). The gap between firstconductive circuit pattern 13 and third conductive circuit pattern 13 bmay be located in the central portion of power semiconductor module 1 inthe second direction (y-direction).

Fourth conductive circuit pattern 14 b is provided on first main face 11m. In particular, fourth conductive circuit pattern 14 b may be providedon fourth insulating substrate segment 11 d. Fourth conductive circuitpattern 14 b is separated from second conductive circuit pattern 14 by agap in the second direction (y-direction). The gap between secondconductive circuit pattern 14 and fourth conductive circuit pattern 14 bmay be located in the central portion of power semiconductor module 1 inthe second direction (y-direction). Fourth conductive circuit pattern 14b is separated from third conductive circuit pattern 13 b by a gap inthe first direction (x-direction). The gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b may belocated in the central portion of power semiconductor module 1 in thefirst direction (x-direction). Each of third conductive circuit pattern13 b and fourth conductive circuit pattern 14 b may be composed of, butis not limited to, a metal material, such as copper or aluminum.

A first conductive member 15 is provided on second main face 11 n. Inparticular, first conductive member 15 may be provided on firstinsulating substrate segment 11 a. A second conductive member 16 isprovided on second main face 11 n. Second conductive member 16 isseparated from first conductive member 15 by a gap in the firstdirection (x-direction). In particular, second conductive member 16 isprovided on second insulating substrate segment 11 b. Each of firstconductive member 15 and second conductive member 16 may be composed of,but is not limited to, a metal material, such as copper or aluminum.

A third conductive member (not shown) is provided on second main face 11n. In particular, the third conductive member may be provided on thirdinsulating substrate segment 11 c. The third conductive member isseparated from first conductive member 15 by a gap in the seconddirection (y-direction). A fourth conductive member (not shown) isprovided on second main face 11 n. The fourth conductive member isseparated from second conductive member 16 by a gap in the seconddirection (y-direction). The fourth conductive member is separated fromthe third conductive member by a gap in the first direction(x-direction). In particular, the fourth conductive member may beprovided on fourth insulating substrate segment 11 d. Each of the thirdconductive member and the fourth conductive member may be composed of,but is not limited to, a metal material, such as copper or aluminum.

Each of first semiconductor device 20, second semiconductor device 21,third semiconductor device 20 b, and fourth semiconductor device 21 bmay be a power semiconductor device, such as an insulated gate bipolartransistor (IGBT) or metal-oxide-semiconductor field-effect transistor(MOSFET); or may be a diode, such as a freewheeling diode. Each of firstsemiconductor device 20, second semiconductor device 21, thirdsemiconductor device 20 b, and fourth semiconductor device 21 b may becomposed of silicon (Si); or a wide-bandgap semiconductor material suchas silicon carbide (SiC), gallium nitride (GaN), or diamond. Firstsemiconductor device 20, second semiconductor device 21, thirdsemiconductor device 20 b, and fourth semiconductor device 21 b may bethe same as or different from one another in terms of at least one ofthe type and the material.

First semiconductor device 20 and second semiconductor device 21 arealigned along the first direction (x-direction). Third semiconductordevice 20 b and fourth semiconductor device 21 b are aligned along thefirst direction (x-direction). First semiconductor device 20 and thirdsemiconductor device 20 b are aligned along the second direction(y-direction). Second semiconductor device 21 and fourth semiconductordevice 21 b are aligned along the second direction (y-direction). Theplurality of semiconductor devices, though aligned in two rows along thefirst direction (x-direction) in the present embodiment, may be alignedin three or more rows along the first direction (x-direction). Theplurality of semiconductor devices, though aligned in two columns alongthe second direction (y-direction) in the present embodiment, may bealigned in one or more columns along the first direction (x-direction).

First semiconductor device 20 is joined to first conductive circuitpattern 13 using a conductive joining member 23, such as solder. Secondsemiconductor device 21 is joined to second conductive circuit pattern14 using a conductive joining member 24, such as solder. Thirdsemiconductor device 20 b is joined to third conductive circuit pattern13 b using a conductive joining member (not shown), such as solder.Fourth semiconductor device 21 b is joined to fourth conductive circuitpattern 14 b using a conductive joining member (not shown), such assolder.

First semiconductor device 20 is electrically connected to a leadterminal 35 via conductive wires 26 and first conductive circuit pattern13. Second semiconductor device 21 is electrically connected to firstsemiconductor device 20 via conductive wires 27 and second conductivecircuit pattern 14. Second semiconductor device 21 is electricallyconnected to a lead terminal 36 via conductive wires 28.

Third semiconductor device 20 b is electrically connected to a leadterminal 35 b via conductive wires 26 b and third conductive circuitpattern 13 b. Fourth semiconductor device 21 b is electrically connectedto third semiconductor device 20 b via conductive wires 27 b and fourthconductive circuit pattern 14 b. Fourth semiconductor device 21 b iselectrically connected to a lead terminal 36 b via conductive wires 28b.

Sealing member 40 seals first semiconductor device 20, secondsemiconductor device 21, first conductive circuit pattern 13, secondconductive circuit pattern 14, and conductive wires 26, 27, 28. Sealingmember 40 has electrical insulation properties. Sealing member 40 mayfurther seal insulating substrate 11. Sealing member 40 may further sealfirst conductive member 15 and second conductive member 16. Sealingmember 40 may further seal third conductive circuit pattern 13 b, fourthconductive circuit pattern 14 b, and conductive wires 26 b, 27 b, 28 b.Sealing member 40 may further seal the third conductive member (notshown) and the fourth conductive member (not shown).

Sealing member 40 may be composed of an insulating resin, such as epoxyresin, silicone resin, urethane resin, polyimide resin, polyamide resin,or acrylic resin.

Sealing member 40 may be composed of an insulating resin material withdispersed fine grain or filler that improves the strength and heatconductivity of sealing member 40. The fine grain or filler thatimproves the strength and heat conductivity of sealing member 40 may becomposed of an inorganic ceramic material, such as silicon dioxide(SiO₂), alumina (Al₂O₃), aluminum nitride (AlN), boron nitride (BN),silicon nitride (Si₃N₄), diamond (C), silicon carbide (SiC), or boronoxide (B₂O₃).

Case 30 may include a base plate 31, an enclosure 32, and lead terminals35, 35 b, 36, 36 b. Base plate 31 is disposed on the opposite side fromfirst and second semiconductor devices 20 and 21 with respect toinsulating substrate 11. Base plate 31 may be composed of, but is notlimited to, a metal material, such as copper (Cu) or aluminum (Al). Baseplate 31 may be composed of, but is not limited to, an alloy of aluminumand silicon carbide (AlSiC), or an alloy of copper and molybdenum(CuMo). Base plate 31 may be composed of, but is not limited to, anorganic material, such as epoxy resin, polyimide resin, acrylic resin,or polyphenylenesulfide (PPS) resin.

Insulating substrate 11 is joined to base plate 31. Specifically, firstinsulating substrate segment 11 a may be bonded to base plate 31 viafirst conductive member 15 and a joining layer 38. Second insulatingsubstrate segment 11 b may be bonded to base plate 31 via secondconductive member 16 and a joining layer 39. Third insulating substratesegment 11 c may be bonded to base plate 31 via the third conductivemember (not shown) and a joining layer (not shown). Fourth insulatingsubstrate segment 11 d may be bonded to base plate 31 via the fourthconductive member (not shown) and a joining layer (not shown). Each ofjoining layers 38, 39 may be composed of a resin adhesive, such as asilicone resin adhesive, or a conductive joining material, such assolder.

Enclosure 32 is bonded to base plate 31. Enclosure 32 includes leadterminals 35, 35 b, 36, 36 b. Enclosure 32 may be composed of anelectrically insulating resin, such as epoxy resin, polyimide resin,acrylic resin, or polyphenylenesulfide (PPS) resin. Lead terminals 35,35 b, 36, 36 b are led out of power semiconductor module 1 throughenclosure 32. Lead terminals 35, 35 b, 36, 36 b do not pass throughfirst barrier layer 50 or are not in contact with first barrier layer50. In the present embodiment, no interface is formed between leadterminals 35, 35 b, 36, 36 b and first barrier layer 50. Accordingly,power semiconductor module 1 can avoid the penetration of moisture andgas through an interface. Each of lead terminals 35, 35 b, 36, 36 b maybe composed of a metal material, such as copper or aluminum.

First barrier layer 50 is disposed on the opposite side from insulatingsubstrate 11 with respect to first and second semiconductor devices 20and 21. First barrier layer 50 is disposed on the opposite side frominsulating substrate 11 with respect to third and fourth semiconductordevices 20 b and 21 b. First barrier layer 50 is provided on or insealing member 40. In the present embodiment, first barrier layer 50 isprovided on sealing member 40. In plan view of first main face 11 m ofinsulating substrate 11, first barrier layer 50 covers firstsemiconductor device 20, second semiconductor device 21, thirdsemiconductor device 20 b, and fourth semiconductor device 21 b. In planview of first main face 11 m of insulating substrate 11, first barrierlayer 50 may cover 80% or more of the area of an outer surface 41 ofsealing member 40; or may cover 90% or more of the area of outer surface41 of sealing member 40; or may cover the whole outer surface 41 ofsealing member 40.

First barrier layer 50 prevents moisture and gas (e.g., sulfur gas) fromentering power semiconductor module 1. First barrier layer 50 preventsor reduces moisture and gas from penetrating to first semiconductordevice 20, second semiconductor device 21, first conductive circuitpattern 13, second conductive circuit pattern 14, insulating substrate11, first conductive member 15, second conductive member 16, andconductive wires 26, 27, 28. First barrier layer 50 can prevent theincrease in leakage current from, for example, first and secondsemiconductor devices 20 and 21; and can prevent the decrease ininsulation performance of, for example, insulating substrate 11 (firstinsulating substrate segment 11 a, second insulating substrate segment11 b).

First barrier layer 50 prevents or reduces moisture and gas frompenetrating to third semiconductor device 20 b, fourth semiconductordevice 21 b, third conductive circuit pattern 13 b, fourth conductivecircuit pattern 14 b, the third conductive member (not shown), thefourth conductive member (not shown), and conductive wires 26 b, 27 b,28 b. First barrier layer 50 can prevent the increase in leakage currentfrom, for example, third and fourth semiconductor devices 20 b and 21 b;and can prevent the decrease in insulation performance of, for example,insulating substrate 11 (third insulating substrate segment 11 c, fourthinsulating substrate segment 11 d).

First barrier layer 50 is composed of a material having low permeabilityto moisture and gas. First barrier layer 50 may be composed of athermoplastic resin, such as polyphenylenesulfide (PPS), polybutyleneterephthalate (PBT), or polyether ether ketone (PEEK); a thermosettingresin; a fluoropolymer, such as polytetrafluoroethylene (PTFE); aceramic or glass material; or a mixture of any of these materials.

At least one of first barrier layer 50 and sealing member 40 includes afirst stress relaxation portion 53. In the present embodiment, firstbarrier layer 50 includes first stress relaxation portion 53. Firstbarrier layer 50 includes a first surface 51 on the side where first andsecond semiconductor devices 20 and 21 are located, and a second surface52 on the side opposite to first surface 51. First stress relaxationportion 53 is a first recess formed in at least one of first surface 51and second surface 52. In the present embodiment shown in FIG. 2, firststress relaxation portion 53 is a first recess formed in second surface52 of first barrier layer 50. First stress relaxation portion 53 may bea first recess formed in first surface 51 of first barrier layer 50, asseen in a power semiconductor module 1 b in a first variation of thepresent embodiment shown in FIG. 3.

The first recess (first stress relaxation portion 53) may be tapered, asseen in a power semiconductor module 1 c in a second variation of thepresent embodiment shown in FIG. 4. The first recess may extend along atleast one of the first direction (x-direction) and second direction(y-direction). The first recess may include a plurality of firstsub-recesses aligned along at least one of the first direction(x-direction) and second direction (y-direction).

Power semiconductor module 1, 1 b, 1 c is composed of a plurality ofmembers having different coefficients of linear thermal expansion, suchas first barrier layer 50, sealing member 40, and insulating substrate11. While in operation or under an ambient temperature change, powersemiconductor module 1, 1 b, 1 c undergoes a temperature change andwarps. First stress relaxation portion 53 reduces stress on firstbarrier layer 50 caused by the warp of power semiconductor module 1, 1b, 1 c. Specifically, first stress relaxation portion 53 in the form ofa first recess reduces the thickness of at least one of first barrierlayer 50 and sealing member 40. The first recess allows at least one offirst barrier layer 50 and sealing member 40 to easily deform inaccordance with the warping deformation of power semiconductor module 1,1 b, 1 c. The first recess thus reduces stress on first barrier layer 50caused by the warp of power semiconductor module 1, 1 b, 1 c, andprevents first barrier layer 50 from cracking.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 overlaps first gap 17 between firstconductive circuit pattern 13 and second conductive circuit pattern 14.In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 may have a smaller width than first gap 17,and may be within first gap 17. In plan view of first main face 11 m ofinsulating substrate 11, first stress relaxation portion 53 may have thesame width as first gap 17, or may have a larger width than first gap17. First stress relaxation portion 53 may be located in the centralportion of power semiconductor module 1, 1 b, 1 c in the first direction(x-direction).

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 overlaps the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, first stressrelaxation portion 53 may have a smaller width than the gap betweenthird conductive circuit pattern 13 b and fourth conductive circuitpattern 14 b, and may be within the gap between third conductive circuitpattern 13 b and fourth conductive circuit pattern 14 b. In plan view offirst main face 11 m of insulating substrate 11, first stress relaxationportion 53 may have the same width as the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b, or mayhave a larger width than the gap between third conductive circuitpattern 13 b and fourth conductive circuit pattern 14 b.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 overlaps the gap between first conductivecircuit pattern 13 and third conductive circuit pattern 13 b. In planview of first main face 11 m of insulating substrate 11, first stressrelaxation portion 53 may have a smaller width than the gap betweenfirst conductive circuit pattern 13 and third conductive circuit pattern13 b, and may be within the gap between first conductive circuit pattern13 and third conductive circuit pattern 13 b. In plan view of first mainface 11 m of insulating substrate 11, first stress relaxation portion 53may have the same width as the gap between first conductive circuitpattern 13 and third conductive circuit pattern 13 b, or may have alarger width than the gap between first conductive circuit pattern 13and third conductive circuit pattern 13 b. First stress relaxationportion 53 may be located in the central portion of power semiconductormodule 1, 1 b, 1 c in the second direction (y-direction).

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 overlaps the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, first stressrelaxation portion 53 may have a smaller width than the gap betweensecond conductive circuit pattern 14 and fourth conductive circuitpattern 14 b, and may be within the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, first stressrelaxation portion 53 may have the same width as the gap between secondconductive circuit pattern 14 and fourth conductive circuit pattern 14b, or may have a larger width than the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 may overlap second gap 12 between firstinsulating substrate segment 11 a and second insulating substratesegment 11 b. In plan view of first main face 11 m of insulatingsubstrate 11, first stress relaxation portion 53 may have a smallerwidth than second gap 12, and may be within second gap 12. In plan viewof first main face 11 m of insulating substrate 11, first stressrelaxation portion 53 may have the same width as second gap 12, or mayhave a larger width than second gap 12.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 may overlap the gap between thirdinsulating substrate segment 11 c and fourth insulating substratesegment 11 d. In plan view of first main face 11 m of insulatingsubstrate 11, first stress relaxation portion 53 may have a smallerwidth than the gap between third insulating substrate segment 11 c andfourth insulating substrate segment 11 d, and may be within the gapbetween third insulating substrate segment 11 c and fourth insulatingsubstrate segment 11 d. In plan view of first main face 11 m ofinsulating substrate 11, first stress relaxation portion 53 may have thesame width as the gap between third insulating substrate segment 11 cand fourth insulating substrate segment 11 d, or may have a larger widththan the gap between third insulating substrate segment 11 c and fourthinsulating substrate segment 11 d.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 may overlap the gap between firstinsulating substrate segment 11 a and third insulating substrate segment11 c. In plan view of first main face 11 m of insulating substrate 11,first stress relaxation portion 53 may have a smaller width than the gapbetween first insulating substrate segment 11 a and third insulatingsubstrate segment 11 c, and may be within the gap between firstinsulating substrate segment 11 a and third insulating substrate segment11 c. In plan view of first main face 11 m of insulating substrate 11,first stress relaxation portion 53 may have the same width as the gapbetween first insulating substrate segment 11 a and third insulatingsubstrate segment 11 c, or may have a larger width than the gap betweenfirst insulating substrate segment 11 a and third insulating substratesegment 11 c.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 53 may overlap the gap between secondinsulating substrate segment 11 b and fourth insulating substratesegment 11 d. In plan view of first main face 11 m of insulatingsubstrate 11, first stress relaxation portion 53 may have a smallerwidth than the gap between second insulating substrate segment 11 b andfourth insulating substrate segment 11 d, and may be within the gapbetween second insulating substrate segment 11 b and fourth insulatingsubstrate segment 11 d. In plan view of first main face 11 m ofinsulating substrate 11, first stress relaxation portion 53 may have thesame width as the gap between second insulating substrate segment 11 band fourth insulating substrate segment 11 d, or may have a larger widththan the gap between second insulating substrate segment 11 b and fourthinsulating substrate segment 11 d.

When power semiconductor module 1, 1 b, 1 c undergoes a temperaturechange and warps, stress concentrates on a portion of first barrierlayer 50 corresponding to the central portion of power semiconductormodule 1, 1 b, 1 c in the first direction (x-direction) andcorresponding to the central portion of power semiconductor module 1, 1b, 1 c in the second direction (y-direction). When power semiconductormodule 1, 1 b, 1 c undergoes a temperature change and warps, stressconcentrates on a portion of first barrier layer 50 corresponding tosecond gap 12 between first insulating substrate segment 11 a and secondinsulating substrate segment 11 b, corresponding to the gap betweenthird insulating substrate segment 11 c and fourth insulating substratesegment 11 d, corresponding to the gap between first insulatingsubstrate segment 11 a and third insulating substrate segment 11 c, andcorresponding to the gap between second insulating substrate segment 11b and fourth insulating substrate segment 11 d. In the presentembodiment, first stress relaxation portion 53 is provided in a portionof first barrier layer 50 susceptible to stress concentration. Firststress relaxation portion 53 effectively prevents first barrier layer 50from cracking.

First stress relaxation portion 53 may be a first through portionconnecting first surface 51 to second surface 52, as seen in a powersemiconductor module 1 d in a third variation of the present embodimentshown in FIG. 5. The first through portion may be a first slot extendingalong at least one of the first direction (x-direction) and seconddirection (y-direction). The first through portion may include aplurality of first through holes aligned along at least one of the firstdirection (x-direction) and second direction (y-direction). The firstthrough portion may separate first barrier layer 50 into a plurality offirst barrier layer segments. A larger power semiconductor module 1 dwill produce an increased stress on first barrier layer 50 when warping.First stress relaxation portion 53 (first through portion) reduces theincreased stress, and prevents first barrier layer 50 from cracking.First stress relaxation portion 53 thus prevents first barrier layer 50from cracking.

The advantageous effects of power semiconductor module 1, 1 b, 1 c, 1 din the present embodiment will now be described.

Power semiconductor module 1, 1 b, 1 c, 1 d in the present embodimentincludes insulating substrate 11, first conductive circuit pattern 13,second conductive circuit pattern 14, first semiconductor device 20,second semiconductor device 21, sealing member 40, and first barrierlayer 50. Insulating substrate 11 includes first main face 11 m. Firstconductive circuit pattern 13 is provided on first main face 11 m.Second conductive circuit pattern 14 is provided on first main face 11m. Second conductive circuit pattern 14 is separated from firstconductive circuit pattern 13 by first gap 17. First semiconductordevice 20 is joined to first conductive circuit pattern 13. Secondsemiconductor device 21 is joined to second conductive circuit pattern14. Sealing member 40 seals first semiconductor device 20, secondsemiconductor device 21, first conductive circuit pattern 13, and secondconductive circuit pattern 14. First barrier layer 50 is disposed on theopposite side from insulating substrate 11 with respect to first andsecond semiconductor devices 20 and 21. First barrier layer 50 isprovided on sealing member 40. At least one of first barrier layer 50and sealing member 40 includes first stress relaxation portion 53.

First barrier layer 50 prevents or reduces moisture and gas frompenetrating to first semiconductor device 20, second semiconductordevice 21, first conductive circuit pattern 13, second conductivecircuit pattern 14, and insulating substrate 11. Further, first stressrelaxation portion 53 reduces stress on first barrier layer 50 caused bythe warp of power semiconductor module 1, 1 b, 1 c, 1 d, and preventsfirst barrier layer 50 from cracking. The reliability of powersemiconductor module 1, 1 b, 1 c, 1 d can thus be improved.

Embodiment 2

With reference to FIG. 6, a power semiconductor module 1 e in embodiment2 will now be described. Power semiconductor module 1 e in the presentembodiment has a configuration similar to that of power semiconductormodule 1, 1 b, 1 c, 1 d in embodiment 1, but differs from powersemiconductor module 1, 1 b, 1 c, 1 d mainly in the following respects.

In power semiconductor module 1 e, first stress relaxation portion 53 isprovided in first barrier layer 50 in such a way that first stressrelaxation portion 53 is at a location corresponding to first conductivecircuit pattern 13, second conductive circuit pattern 14, and first gap17. The thickness of first barrier layer 50 gradually decreases toward afirst portion 55 of first barrier layer 50 at least in first stressrelaxation portion 53. In plan view of first main face 11 m ofinsulating substrate 11, first portion 55 overlaps first gap 17 betweenfirst conductive circuit pattern 13 and second conductive circuitpattern 14. In plan view of first main face 11 m of insulating substrate11, first portion 55 is located within first gap 17. In plan view offirst main face 11 m of insulating substrate 11, first portion 55 islocated within second gap 12. First portion 55 is located in the centralportion of power semiconductor module 1 e in the first direction(x-direction). The thickness of first barrier layer 50 is smallest atfirst portion 55 of first stress relaxation portion 53.

First barrier layer 50 is similarly configured in the portioncorresponding to third conductive circuit pattern 13 b, fourthconductive circuit pattern 14 b, and the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b. Firstbarrier layer 50 may be similarly configured in the portioncorresponding to first conductive circuit pattern 13, third conductivecircuit pattern 13 b, and the gap between first conductive circuitpattern 13 and third conductive circuit pattern 13 b. First barrierlayer 50 may be similarly configured in the portion corresponding tosecond conductive circuit pattern 14, fourth conductive circuit pattern14 b, and the gap between second conductive circuit pattern 14 andfourth conductive circuit pattern 14 b.

Power semiconductor module 1 e in the present embodiment has thefollowing advantageous effects, similar to power semiconductor module 1,1 b, 1 c, 1 d in embodiment 1. The thickness of first barrier layer 50is smallest at first portion 55 of first stress relaxation portion 53.First stress relaxation portion 53 allows at least one of first barrierlayer 50 and sealing member 40 to easily deform in accordance with thewarping deformation of power semiconductor module 1 e. First stressrelaxation portion 53 reduces stress on first barrier layer 50 caused bythe warp of power semiconductor module 1 e, and prevents first barrierlayer 50 from cracking. The reliability of power semiconductor module 1e can thus be improved.

Embodiment 3

With reference to FIG. 7, a power semiconductor module 1 f in embodiment3 will now be described. Power semiconductor module 1 f in the presentembodiment has a configuration similar to that of power semiconductormodule 1, 1 b, 1 c, 1 d in embodiment 1, but differs from powersemiconductor module 1, 1 b, 1 c, 1 d mainly in the following respects.

In power semiconductor module 1 f, sealing member 40 includes a firststress relaxation portion 43. First stress relaxation portion 43 is asecond recess formed in outer surface 41 of sealing member 40. Thesecond recess may extend along at least one of the first direction(x-direction) and second direction (y-direction). The second recess mayinclude a plurality of second sub-recesses aligned along at least one ofthe first direction (x-direction) and second direction (y-direction).The second recess (first stress relaxation portion 43) may be tapered,as seen in a power semiconductor module 1 g in a variation of thepresent embodiment shown in FIG. 8.

In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 43 overlaps first gap 17 between firstconductive circuit pattern 13 and second conductive circuit pattern 14.In plan view of first main face 11 m of insulating substrate 11, firststress relaxation portion 43 may have a smaller width than first gap 17,and may be within first gap 17. In plan view of first main face 11 m ofinsulating substrate 11, first stress relaxation portion 43 may have thesame width as first gap 17, or may have a larger width than first gap17. In plan view of first main face 11 m of insulating substrate 11,first stress relaxation portion 43 overlaps second gap 12 between firstinsulating substrate segment 11 a and second insulating substratesegment 11 b. First stress relaxation portion 43 is located in thecentral portion of power semiconductor module 1 f, 1 g in the firstdirection (x-direction).

First barrier layer 50 includes a protrusion 56 protruding from firstsurface 51. Protrusion 56 may be complementary to the second recess(first stress relaxation portion 43) in shape. In plan view of firstmain face 11 m of insulating substrate 11, protrusion 56 overlaps firstgap 17 between first conductive circuit pattern 13 and second conductivecircuit pattern 14. In particular, in plan view of first main face 11 mof insulating substrate 11, protrusion 56 is located within first gap17. In plan view of first main face 11 m of insulating substrate 11,protrusion 56 overlaps second gap 12 between first insulating substratesegment 11 a and second insulating substrate segment 11 b. Protrusion 56is located in the central portion of power semiconductor module 1 f, 1 gin the first direction (x-direction).

Sealing member 40 is similarly configured in the portion correspondingto third conductive circuit pattern 13 b, fourth conductive circuitpattern 14 b, and the gap between third conductive circuit pattern 13 band fourth conductive circuit pattern 14 b. Sealing member 40 may besimilarly configured in the portion corresponding to first conductivecircuit pattern 13, third conductive circuit pattern 13 b, and the gapbetween first conductive circuit pattern 13 and third conductive circuitpattern 13 b. Sealing member 40 may be similarly configured in theportion corresponding to second conductive circuit pattern 14, fourthconductive circuit pattern 14 b, and the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b.

In plan view of first main face 11 m of insulating substrate 11,protrusion 56 of first barrier layer 50 overlaps the gap between thirdconductive circuit pattern 13 b and fourth conductive circuit pattern 14b. In particular, in plan view of first main face 11 m of insulatingsubstrate 11, protrusion 56 is located within the gap between thirdconductive circuit pattern 13 b and fourth conductive circuit pattern 14b. In plan view of first main face 11 m of insulating substrate 11,protrusion 56 overlaps the gap between first insulating substratesegment 11 a and second insulating substrate segment 11 b. Protrusion 56is located in the central portion of power semiconductor module 1 f, 1 gin the second direction (y-direction).

Power semiconductor module 1 f, 1 g in the present embodiment has thefollowing advantageous effects, similar to power semiconductor module 1,1 b, 1 c, 1 d in embodiment 1. First stress relaxation portion 43 allowsat least one of first barrier layer 50 and sealing member 40 to easilydeform in accordance with the warping deformation of power semiconductormodule 1 f, 1 g. First stress relaxation portion 43 reduces stress onfirst barrier layer 50 caused by the warp of power semiconductor module1 f, 1 g, and prevents first barrier layer 50 from cracking. Thereliability of power semiconductor module 1 f, 1 g can thus be improved.

Embodiment 4

With reference to FIG. 9, a power semiconductor module 1 h in embodiment4 will now be described. Power semiconductor module 1 h in the presentembodiment has a configuration similar to that of power semiconductormodule 1 f, 1 g in embodiment 3, but differs from power semiconductormodule 1 f, 1 g mainly in the following respects.

In power semiconductor module 1 h, first stress relaxation portion 43 isprovided in sealing member 40 in such a way that first stress relaxationportion 43 is at a location corresponding to first conductive circuitpattern 13, second conductive circuit pattern 14, and first gap 17.Outer surface 41 of sealing member 40 is gradually recessed toward asecond portion 45 of outer surface 41 at least in first stressrelaxation portion 43. In plan view of first main face 11 m ofinsulating substrate 11, second portion 45 overlaps first gap 17 betweenfirst conductive circuit pattern 13 and second conductive circuitpattern 14. In particular, in plan view of first main face 11 m ofinsulating substrate 11, second portion 45 is located within first gap17. First stress relaxation portion 43 overlaps second gap 12 betweenfirst insulating substrate segment 11 a and second insulating substratesegment 11 b. Second portion 45 is located in the central portion ofpower semiconductor module 1 h in the first direction (x-direction).Outer surface 41 of sealing member 40 is recessed deepest at secondportion 45 of first stress relaxation portion 43.

Outer surface 41 of sealing member 40 is similarly configured in theportion corresponding to third conductive circuit pattern 13 b, fourthconductive circuit pattern 14 b, and the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b. Outersurface 41 of sealing member 40 may be similarly configured in theportion corresponding to first conductive circuit pattern 13, thirdconductive circuit pattern 13 b, and the gap between first conductivecircuit pattern 13 and third conductive circuit pattern 13 b. Outersurface 41 of sealing member 40 may be similarly configured in theportion corresponding to second conductive circuit pattern 14, fourthconductive circuit pattern 14 b, and the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b.

Power semiconductor module 1 h in the present embodiment has thefollowing advantageous effects, similar to power semiconductor module 1f, 1 g in embodiment 3. Outer surface 41 of sealing member 40 isrecessed deepest at second portion 45 of first stress relaxation portion43. First stress relaxation portion 43 allows at least one of firstbarrier layer 50 and sealing member 40 to easily deform in accordancewith the warping deformation of power semiconductor module 1 h. Firststress relaxation portion 43 reduces stress on first barrier layer 50caused by the warp of power semiconductor module 1 h, and prevents firstbarrier layer 50 from cracking. The reliability of power semiconductormodule 1 h can thus be improved.

Embodiment 5

With reference to FIG. 10, a power semiconductor module 1 i inembodiment 5 will now be described. Power semiconductor module 1 i inthe present embodiment has a configuration similar to that of powersemiconductor module 1 in embodiment 1, but differs from powersemiconductor module 1 mainly in the following respects. In powersemiconductor module 1 i, first barrier layer 50 is provided in sealingmember 40. First stress relaxation portion 53 may be a first throughportion connecting first surface 51 to second surface 52, as seen in apower semiconductor module 1 j in a variation of the present embodimentshown in FIG. 11.

Power semiconductor module 1 i, 1 j in the present embodiment has thefollowing advantageous effects in addition to those of powersemiconductor module 1, 1 d in embodiment 1. First barrier layer 50 isprovided in sealing member 40. Sealing member 40 is not exposed tooxygen in the air. This prevents sealing member 40 from oxidation anddeterioration when power semiconductor module 1 i, 1 j is operating andrises to a high temperature. The reliability of power semiconductormodule 1 i, 1 j can thus be improved.

Embodiment 6

With reference to FIG. 12, a power semiconductor module 1 k inembodiment 6 will now be described. Power semiconductor module 1 k inthe present embodiment has a configuration similar to that of powersemiconductor module 1 b in the first variation of embodiment 1, butdiffers from power semiconductor module 1 b mainly in the followingrespects. At least a part of the first recess is a cavity 58 which isnot filled with sealing member 40. In particular, the whole of firstrecess is cavity 58.

Power semiconductor module 1 k in the present embodiment has thefollowing advantageous effects in addition to those of powersemiconductor module 1, 1 b in embodiment 1. In power semiconductormodule 1 k in the present embodiment, first barrier layer 50 is providedon sealing member 40. The first recess is formed in first surface 51. Atleast a part of the first recess is cavity 58 which is not filled withsealing member 40. A larger power semiconductor module 1 k will producean increased stress on first barrier layer 50 when warping. Cavity 58reduces the increased stress, and prevents first barrier layer 50 fromcracking. The reliability of power semiconductor module 1 k can thus befurther improved.

Embodiment 7

With reference to FIGS. 13 and 14, a power semiconductor module 1 m inembodiment 7 will now be described. Power semiconductor module 1 m inthe present embodiment has a configuration and advantageous effectssimilar to those of power semiconductor module 1 in embodiment 1, butdiffers from power semiconductor module 1 mainly in the followingrespects.

Power semiconductor module 1 m further includes a second barrier layer60 such that second barrier layer 60 and first barrier layer 50 arestacked. Sealing member 40 may be interposed between first barrier layer50 and second barrier layer 60. In the present embodiment, secondbarrier layer 60 is closer to first and second semiconductor devices 20and 21 than first barrier layer 50 is to first and second semiconductordevices 20 and 21. Second barrier layer 60 is disposed between firstbarrier layer 50, and first and second semiconductor devices 20 and 21.Second barrier layer 60 is provided in sealing member 40. Second barrierlayer 60 may be remoter from first and second semiconductor devices 20and 21 than first barrier layer 50 is from first and secondsemiconductor devices 20 and 21.

In plan view of first main face 11 m of insulating substrate 11, secondbarrier layer 60 covers first semiconductor device 20, secondsemiconductor device 21, third semiconductor device 20 b, and fourthsemiconductor device 21 b. In plan view of first main face 11 m ofinsulating substrate 11, second barrier layer 60 may cover 80% or moreof the area of outer surface 41 of sealing member 40; or may cover 90%or more of the area of outer surface 41 of sealing member 40; or maycover the whole outer surface 41 of sealing member 40.

In the present embodiment, in plan view of first main face 11 m ofinsulating substrate 11, second barrier layer 60 has a larger area thanfirst barrier layer 50. In plan view of first main face 11 m ofinsulating substrate 11, the second outer periphery of second barrierlayer 60 is located on the outer side relative to the first outerperiphery of first barrier layer 50. In plan view of first main face 11m of insulating substrate 11, second barrier layer 60 may have the samearea as first barrier layer 50, or may have a smaller area than firstbarrier layer 50. In plan view of first main face 11 m of insulatingsubstrate 11, the second outer periphery of second barrier layer 60 mayalign with the first outer periphery of first barrier layer 50, or maybe on the inner side relative to the first outer periphery of firstbarrier layer 50.

Second barrier layer 60 prevents moisture and gas (e.g., sulfur gas)from entering power semiconductor module 1 m. Second barrier layer 60prevents or reduces moisture and gas from penetrating to firstsemiconductor device 20, second semiconductor device 21, firstconductive circuit pattern 13, second conductive circuit pattern 14,insulating substrate 11, first conductive member 15, and secondconductive member 16. Second barrier layer 60 can prevent the increasein leakage current from, for example, first and second semiconductordevices 20 and 21; and can prevent the decrease in insulationperformance of, for example, insulating substrate 11 (first insulatingsubstrate segment 11 a, second insulating substrate segment 11 b).

Second barrier layer 60 prevents or reduces moisture and gas frompenetrating to third semiconductor device 20 b, fourth semiconductordevice 21 b, third conductive circuit pattern 13 b, fourth conductivecircuit pattern 14 b, the third conductive member (not shown), and thefourth conductive member (not shown). Second barrier layer 60 canprevent the increase in leakage current from third and fourthsemiconductor devices 20 b and 21 b; and can prevent the insulationperformance of, for example, insulating substrate 11 (third insulatingsubstrate segment 11 c, fourth insulating substrate segment 11 d).

Second barrier layer 60 is composed of a material having lowpermeability to moisture and gas. Second barrier layer 60 may becomposed of a thermoplastic resin, such as polyphenylenesulfide (PPS),polybutylene terephthalate (PBT), or polyether ether ketone (PEEK); athermosetting resin; a fluoropolymer, such as polytetrafluoroethylene(PTFE); a ceramic or glass material; or a mixture of any of thesematerials.

At least one of second barrier layer 60 and sealing member 40 includes asecond stress relaxation portion 63. In the present embodiment, secondbarrier layer 60 includes second stress relaxation portion 63. Secondbarrier layer 60 includes a third surface 61 on the side where first andsecond semiconductor devices 20 and 21 are located, and a fourth surface62 on the side opposite to third surface 61. Second stress relaxationportion 63 is a third recess formed in at least one of third surface 61and fourth surface 62. The third recess may extend along at least one ofthe first direction (x-direction) and second direction (y-direction).The third recess may include a plurality of third sub-recesses alignedalong at least one of the first direction (x-direction) and seconddirection (y-direction). In plan view of first main face 11 m ofinsulating substrate 11, at least a part of second stress relaxationportion 63 may overlap first stress relaxation portion 53.

In the present embodiment shown in FIG. 14, second stress relaxationportion 63 may be a third recess formed in fourth surface 62 of secondbarrier layer 60. The third recess in second barrier layer 60 may have asmaller width than the first recess in first barrier layer 50. The thirdrecess in second barrier layer 60 may have a larger width than the firstrecess in first barrier layer 50, as seen in a power semiconductormodule 1 n in a first variation of the present embodiment shown in FIG.15. The third recess in second barrier layer 60 may have the same widthas the first recess in first barrier layer 50.

While in operation or under an ambient temperature change, powersemiconductor module 1 m, 1 n undergoes a temperature change and warps.Second stress relaxation portion 63 reduces stress on second barrierlayer 60 caused by the warp of power semiconductor module 1 m, 1 n.Specifically, second stress relaxation portion 63 in the form of a thirdrecess reduces the thickness of at least one of second barrier layer 60and sealing member 40. The third recess allows at least one of secondbarrier layer 60 and sealing member 40 to easily deform in accordancewith the warping deformation of power semiconductor module 1 m, 1 n. Thethird recess reduces stress on second barrier layer 60 caused by thewarp of power semiconductor module 1 m, 1 n, and prevents second barrierlayer 60 from cracking.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 overlaps first gap 17 between firstconductive circuit pattern 13 and second conductive circuit pattern 14.In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 may have a smaller width than first gap 17,and may be within first gap 17. In plan view of first main face 11 m ofinsulating substrate 11, second stress relaxation portion 63 may havethe same width as first gap 17, or may have a larger width than firstgap 17.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 overlaps the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have a smaller width than the gap betweenthird conductive circuit pattern 13 b and fourth conductive circuitpattern 14 b, and may be within the gap between third conductive circuitpattern 13 b and fourth conductive circuit pattern 14 b. In plan view offirst main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have the same width as the gap between thirdconductive circuit pattern 13 b and fourth conductive circuit pattern 14b, or may have a larger width than the gap between third conductivecircuit pattern 13 b and fourth conductive circuit pattern 14 b.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 overlaps the gap between first conductivecircuit pattern 13 and third conductive circuit pattern 13 b. In planview of first main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have a smaller width than the gap betweenfirst conductive circuit pattern 13 and third conductive circuit pattern13 b, and may be within the gap between first conductive circuit pattern13 and third conductive circuit pattern 13 b. In plan view of first mainface 11 m of insulating substrate 11, second stress relaxation portion63 may have the same width as the gap between first conductive circuitpattern 13 and third conductive circuit pattern 13 b, or may have alarger width than the gap between first conductive circuit pattern 13and third conductive circuit pattern 13 b.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 overlaps the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have a smaller width than the gap betweensecond conductive circuit pattern 14 and fourth conductive circuitpattern 14 b, and may be within the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b. In planview of first main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have the same width as the gap between secondconductive circuit pattern 14 and fourth conductive circuit pattern 14b, or may have a larger width than the gap between second conductivecircuit pattern 14 and fourth conductive circuit pattern 14 b.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 may overlap second gap 12 between firstinsulating substrate segment 11 a and second insulating substratesegment 11 b. In plan view of first main face 11 m of insulatingsubstrate 11, second stress relaxation portion 63 may have a smallerwidth than second gap 12, and may be within second gap 12. In plan viewof first main face 11 m of insulating substrate 11, second stressrelaxation portion 63 may have the same width as second gap 12, or mayhave a larger width than second gap 12.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 may overlap the gap between thirdinsulating substrate segment 11 c and fourth insulating substratesegment 11 d. In plan view of first main face 11 m of insulatingsubstrate 11, second stress relaxation portion 63 may have a smallerwidth than the gap between third insulating substrate segment 11 c andfourth insulating substrate segment 11 d, and may be within the gapbetween third insulating substrate segment 11 c and fourth insulatingsubstrate segment 11 d. In plan view of first main face 11 m ofinsulating substrate 11, second stress relaxation portion 63 may havethe same width as the gap between third insulating substrate segment 11c and fourth insulating substrate segment 11 d, or may have a largerwidth than the gap between third insulating substrate segment 11 c andfourth insulating substrate segment 11 d.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 may overlap the gap between firstinsulating substrate segment 11 a and third insulating substrate segment11 c. In plan view of first main face 11 m of insulating substrate 11,second stress relaxation portion 63 may have a smaller width than thegap between first insulating substrate segment 11 a and third insulatingsubstrate segment 11 c, and may be within the gap between firstinsulating substrate segment 11 a and third insulating substrate segment11 c. In plan view of first main face 11 m of insulating substrate 11,second stress relaxation portion 63 may have the same width as the gapbetween first insulating substrate segment 11 a and third insulatingsubstrate segment 11 c, or may have a larger width than the gap betweenfirst insulating substrate segment 11 a and third insulating substratesegment 11 c.

In plan view of first main face 11 m of insulating substrate 11, secondstress relaxation portion 63 may overlap the gap between secondinsulating substrate segment 11 b and fourth insulating substratesegment 11 d. In plan view of first main face 11 m of insulatingsubstrate 11, second stress relaxation portion 63 may have a smallerwidth than the gap between second insulating substrate segment 11 b andfourth insulating substrate segment 11 d, and may be within the gapbetween second insulating substrate segment 11 b and fourth insulatingsubstrate segment 11 d. In plan view of first main face 11 m ofinsulating substrate 11, second stress relaxation portion 63 may havethe same width as the gap between second insulating substrate segment 11b and fourth insulating substrate segment 11 d, or may have a largerwidth than the gap between second insulating substrate segment 11 b andfourth insulating substrate segment 11 d.

When power semiconductor module 1 m, 1 n undergoes a temperature changeand warps, stress concentrates on a portion of second barrier layer 60corresponding to the central portion of power semiconductor module 1 m,1 n in the first direction (x-direction) and corresponding to thecentral portion of power semiconductor module 1 m, 1 n in the seconddirection (y-direction). When power semiconductor module 1 m, 1 nundergoes a temperature change and warps, stress concentrates on aportion of first barrier layer 50 corresponding to second gap 12 betweenfirst insulating substrate segment 11 a and second insulating substratesegment 11 b, corresponding to the gap between third insulatingsubstrate segment 11 c and fourth insulating substrate segment 11 d,corresponding to the gap between first insulating substrate segment 11 aand third insulating substrate segment 11 c, and corresponding to thegap between second insulating substrate segment 11 b and fourthinsulating substrate segment 11 d. In the present embodiment, secondstress relaxation portion 63 is provided in a portion of second barrierlayer 60 susceptible to stress concentration. Second stress relaxationportion 63 effectively prevents second barrier layer 60 from cracking.

Second stress relaxation portion 63 may be a second through portionconnecting third surface 61 to fourth surface 62, as seen in a powersemiconductor module 1 p in a second variation of the present embodimentshown in FIG. 16. The second through portion may be a second slotextending along at least one of the first direction (x-direction) andsecond direction (y-direction). The second through portion may include aplurality of second through holes aligned along at least one of thefirst direction (x-direction) and second direction (y-direction). Thesecond through portion may separate second barrier layer 60 into aplurality of second barrier layer segments. In plan view of first mainface 11 m of insulating substrate 11, at least a part of second stressrelaxation portion 63 (second through portion) overlaps first barrierlayer 50. In particular, in plan view of first main face 11 m ofinsulating substrate 11, the whole of second stress relaxation portion63 (second through portion) overlaps first barrier layer 50.

A larger power semiconductor module 1 p will produce an increased stresson second barrier layer 60 when warping. Second stress relaxationportion 63 (second through portion) reduces the increased stress, andprevents second barrier layer 60 from cracking. Second stress relaxationportion 63 thus prevents second barrier layer 60 from cracking.

Power semiconductor module 1 m, 1 n, 1 p in the present embodiment hasthe following advantageous effects in addition to those of powersemiconductor module 1 in embodiment 1. Power semiconductor module 1 m,1 n, 1 p further includes second barrier layer 60 such that secondbarrier layer 60 and first barrier layer 50 are stacked. Second barrierlayer 60 prevents or reduces moisture and gas from penetrating to firstsemiconductor device 20, second semiconductor device 21, firstconductive circuit pattern 13, second conductive circuit pattern 14, andinsulating substrate 11. The reliability of power semiconductor module 1m, 1 n, 1 p can thus be further improved.

In power semiconductor module 1 m, 1 n, 1 p, at least one of secondbarrier layer 60 and sealing member 40 includes second stress relaxationportion 63. Second stress relaxation portion 63 allows at least one ofsecond barrier layer 60 and sealing member 40 to easily deform inaccordance with the warping deformation of power semiconductor module 1m, 1 n, 1 p. Second stress relaxation portion 63 reduces stress onsecond barrier layer 60 caused by the warp of power semiconductor module1 m, 1 n, 1 p, and prevents second barrier layer 60 from cracking. Thereliability of power semiconductor module 1 m, 1 n, 1 p can thus beimproved.

Embodiment 8

With reference to FIG. 17, a power semiconductor module 1 q inembodiment 8 will now be described. Power semiconductor module 1 q inthe present embodiment has a configuration and advantageous effectssimilar to those of power semiconductor module 1 m in embodiment 7, butdiffers from power semiconductor module 1 m mainly in the followingrespects.

In power semiconductor module 1 q, first stress relaxation portion 53 isa first through portion connecting first surface 51 to second surface52. The first through portion may be a first slot extending along atleast one of the first direction (x-direction) and second direction(y-direction). The first through portion may include a plurality offirst through holes aligned along at least one of the first direction(x-direction) and second direction (y-direction). The first throughportion may separate first barrier layer 50 into a plurality of firstbarrier layer segments. In plan view of first main face 11 m ofinsulating substrate 11, at least a part of first stress relaxationportion 53 (first through portion) overlaps second barrier layer 60. Inparticular, in plan view of first main face 11 m of insulating substrate11, the whole of first stress relaxation portion 53 (first throughportion) overlaps second barrier layer 60.

Power semiconductor module 1 q in the present embodiment has thefollowing advantageous effects in addition to those of powersemiconductor module 1 m in embodiment 7. A larger power semiconductormodule 1 q will produce an increased stress on first barrier layer 50when warping. First stress relaxation portion 53 (first through portion)reduces the increased stress, and prevents first barrier layer 50 fromcracking. Further, second barrier layer 60 prevents or reduces moistureand gas, which has entered through first stress relaxation portion 53(first through portion), from penetrating to first semiconductor device20, second semiconductor device 21, first conductive circuit pattern 13,second conductive circuit pattern 14, and insulating substrate 11. Thereliability of power semiconductor module 1 q can thus be improved.

Embodiment 9

With reference to FIG. 18, a power semiconductor module 1 r inembodiment 9 will now be described. Power semiconductor module 1 r inthe present embodiment has a configuration and advantageous effectssimilar to those of power semiconductor module 1 in embodiment 1, butdiffers from power semiconductor module 1 mainly in the followingrespects.

Instead of base plate 31 (FIG. 2), insulating substrate 11 and firstconductive member 15 may form a part of a case 30 q. In the presentembodiment, insulating substrate 11 is a single plate that is notdivided into first insulating substrate segment 11 a, second insulatingsubstrate segment 11 b, third insulating substrate segment 11 c, andfourth insulating substrate segment 11 d. First conductive member 15lies under first conductive circuit pattern 13, second conductivecircuit pattern 14, and enclosure 32, with insulating substrate 11 beinginterposed between first conductive member 15 and these components 13,14, and 32. First conductive member 15 may also lie under thirdconductive circuit pattern 13 b and fourth conductive circuit pattern 14b, with insulating substrate 11 being interposed between firstconductive member 15 and these components 13 b and 14 b. Secondconductive member 16, the third conductive member (not shown), and thefourth conductive member (not shown) are not formed on second main face11 n of insulating substrate 11.

Embodiment 10

Embodiment 10 is an application of power semiconductor module 1, 1 b, 1c, 1 d, 1 e, 1 f, 1 g, 1 h, 1 i, 1 j, 1 l, 1 m, 1 n, 1 p, 1 q, 1 raccording to any one of embodiments 1 to 9 to a power conversionapparatus. Here, a power conversion apparatus 200 in the presentembodiment may be, but is not limited to, a three-phase inverter.

The power conversion system shown in FIG. 19 includes a power supply100, power conversion apparatus 200, and a load 300. Power supply 100 isa DC power supply that supplies DC power to power conversion apparatus200. Power supply 100 may be, but is not limited to, a DC system, asolar cell, or a storage battery; or may be a rectifier circuit orAC-to-DC converter connected to an AC system. Power supply 100 may be aDC-to-DC converter that converts DC power from a DC system into other DCpower.

Power conversion apparatus 200, which is a three-phase inverterconnected between power supply 100 and load 300, converts DC power frompower supply 100 into AC power and supplies the AC power to load 300. Asshown in FIG. 19, power conversion apparatus 200 includes a mainconversion circuit 201 that converts DC power into AC power and outputsthe AC power, and a control circuit 203 that outputs a control signal tomain conversion circuit 201 for controlling main conversion circuit 201.

Load 300 is a three-phase electric motor that is driven by AC power frompower conversion apparatus 200. Load 300 may be, but is not limited to,an electric motor for a variety of electrical equipment, such as ahybrid vehicle, an electric vehicle, a railway vehicle, an elevator, oran air conditioner.

Power conversion apparatus 200 will now be described in detail. Mainconversion circuit 201 includes switching devices (not shown) andfreewheeling diodes (not shown). Main conversion circuit 201 switchesthe voltage from power supply 100 using the switching devices, therebyconverting DC power from power supply 100 into AC power to supply the ACpower to load 300. Main conversion circuit 201 may have a variety ofspecific circuit configurations. Main conversion circuit 201 accordingto the present embodiment may be a two-level three-phase full-bridgecircuit including six switching devices and six freewheeling diodes eachconnected in antiparallel to a corresponding one of the switchingdevices. Power semiconductor module 1, 1 b, 1 c, 1 d, 1 e, 1 f, 1 g, 1h, 1 j, 1 k, 1 m, 1 n, 1 p, 1 q, 1 r in any one of embodiments 1 to 9described above can be applied to at least any one of a set of switchingdevices and a set of freewheeling diodes in main conversion circuit 201.Power semiconductor module 1, 1 b, 1 c, 1 d, 1 e, 1 f, 1 g, 1 h, 1 i, 1j, 1 k, 1 m, 1 n, 1 p, 1 q, 1 r in any one of embodiments 1 to 9described above can be applied to power semiconductor module 202included in main conversion circuit 201. The six switching devices formsets of upper and lower arms, each of which includes two switchingdevices connected in series. Each set of upper and lower arms is for acorresponding one of the phases (U, V, and W phases) of the full-bridgecircuit. The output terminals of the respective sets of upper and lowerarms, i.e., three output terminals of main conversion circuit 201, areconnected to load 300.

Main conversion circuit 201 includes drive circuits (not shown) to drivethe respective switching devices. The drive circuits may be incorporatedin, or provided outside of, power semiconductor module 202. Each drivecircuit generates a drive signal for driving a corresponding switchingdevice included in main conversion circuit 201, and supplies the drivesignal to the control electrode of the switching device in mainconversion circuit 201. Specifically, each drive circuit outputs a drivesignal to the control electrode of a corresponding switching device, inaccordance with a control signal from control circuit 203. The drivesignal is for turning on or off the switching device.

In power conversion apparatus 200 according to the present embodiment,power semiconductor module 1, 1 b, 1 c, 1 d, 1 e, 1 f, 1 g, 1 h, 1 j, 1k, 1 m, 1 n, 1 p, 1 q, 1 r according to any one of embodiments 1 to 9 isapplied to power semiconductor module 202 included in main conversioncircuit 201. Thus, power conversion apparatus 200 according to thepresent embodiment has improved reliability.

Although the present embodiment describes an application of the presentinvention to a two-level three-phase inverter, this is not a limitation.The present invention may be applied to a variety of power conversionapparatuses. The two-level power conversion apparatus in the presentembodiment may instead be a three-level or multilevel power conversionapparatus. If the power conversion apparatus supplies power to asingle-phase load, the present invention may be applied to asingle-phase inverter. If the power conversion apparatus supplies powerto a DC load or the like, the present invention may be applied to aDC-to-DC converter or an AC-to-DC converter.

The power conversion apparatus to which the present invention is appliedis not limited to a case where an electric motor is used as a load. Thepower conversion apparatus may be incorporated in a power supply for,for example, an electric discharge machine or laser beam machine, or apower supply for an induction heating cooker or wireless poweringsystem. The power conversion apparatus to which the present invention isapplied may be used as a power conditioner for a photovoltaic system, anelectricity storage system or the like.

It should be understood that embodiments 1 to 10 disclosed herein are byway of example in every respect, not by way of limitation. Two or moreof embodiments 1 to 10 disclosed herein may be combined wherecompatible. The scope of the present invention is defined not by theabove description but by the terms of the claims, and is intended toinclude any modification within the meaning and scope equivalent to theterms of the claims.

REFERENCE SIGNS LIST

-   -   1, 1 b, 1 c, 1 d, 1 e, 1 f, 1 g, 1 h, 1 i, 1 j, 1 k, 1 m, 1 n, 1        p, 1 q, 1 r: power semiconductor module; 11: insulating        substrate; 11 a: first insulating substrate segment; 11 b:        second insulating substrate segment; 11 c: third insulating        substrate segment; 11 d: fourth insulating substrate segment; 11        m: first main face; 11 n: second main face; 12: second gap; 13:        first conductive circuit pattern; 13 b: third conductive circuit        pattern; 14: second conductive circuit pattern; 14 b: fourth        conductive circuit pattern; 15: first conductive member; 16:        second conductive member; 17: first gap; 20: first semiconductor        device; 20 b: third semiconductor device; 21: second        semiconductor device; 21 b: fourth semiconductor device; 23, 24:        conductive joining member; 26, 26 b, 27, 27 b, 28, 28 b:        conductive wire; 30, 30 q: case; 31: base plate; 32: enclosure;        35, 35 b, 36, 36 b: lead terminal; 38, 39: joining layer; 40:        sealing member; 41: outer surface; 43, 53: first stress        relaxation portion; 45: second portion; 50: first barrier layer;        51: first surface; 52: second surface; 55: first portion; 56:        protrusion; 58: cavity; 60: second barrier layer; 61: third        surface; 62: fourth surface; 63: second stress relaxation        portion; 100: power supply; 200: power conversion apparatus;        201: main conversion circuit; 202: power semiconductor module;        203: control circuit; 300: load

1. A power semiconductor module comprising: an insulating substrateincluding a first main face; a first conductive circuit pattern providedon the first main face; a second conductive circuit pattern provided onthe first main face, the second conductive circuit pattern beingseparated from the first conductive circuit pattern by a first gap; afirst semiconductor device joined to the first conductive circuitpattern; a second semiconductor device joined to the second conductivecircuit pattern; a sealing member sealing the first semiconductordevice, the second semiconductor device, the first conductive circuitpattern, and the second conductive circuit pattern; and a first barrierlayer disposed on an opposite side from the insulating substrate withrespect to the first semiconductor device and the second semiconductordevice, the first barrier layer being provided on or in the sealingmember, at least one of the first barrier layer and the sealing memberincluding a first stress relaxation portion, in plan view of the firstmain face, the first stress relaxation portion overlapping the first gapin such a way that a center of the first gap is within the first stressrelaxation portion.
 2. The power semiconductor module according to claim1, wherein the first barrier layer includes a first surface on a sidewhere the first semiconductor device and the second semiconductor deviceare located, and a second surface on a side opposite to the firstsurface, and the first stress relaxation portion is a first recessformed in at least one of the first surface and the second surface. 3.The power semiconductor module according to claim 2, wherein the firstbarrier layer is provided on the sealing member, the first recess isformed in the first surface, and at least a part of the first recess isa cavity which is not filled with the sealing member.
 4. The powersemiconductor module according to claim 1, wherein the first barrierlayer includes a first surface on a side where the first semiconductordevice and the second semiconductor device are located, and a secondsurface on a side opposite to the first surface, and the first stressrelaxation portion is a first through portion connecting the firstsurface to the second surface.
 5. The power semiconductor moduleaccording to claim 1, wherein the sealing member includes an outersurface, and the first stress relaxation portion is a second recessformed in the outer surface.
 6. (canceled)
 7. The power semiconductormodule according to claim 2, wherein the first stress relaxation portionis provided in the first barrier layer in such a way that the firststress relaxation portion is at a location corresponding to the firstconductive circuit pattern, the second conductive circuit pattern, andthe first gap, a thickness of the first barrier layer graduallydecreases toward a first portion of the first barrier layer at least inthe first stress relaxation portion, wherein the first portion overlapsthe first gap in plan view of the first main face, and the thickness ofthe first barrier layer is smallest at the first portion of the firststress relaxation portion.
 8. The power semiconductor module accordingto claim 5, wherein the first stress relaxation portion is provided inthe sealing member in such a way that the first stress relaxationportion is at a location corresponding to the first conductive circuitpattern, the second conductive circuit pattern, and the first gap, andthe outer surface is gradually recessed toward a second portion of theouter surface at least in the first stress relaxation portion, whereinthe second portion overlaps the first gap in plan view of the first mainface, and the outer surface is recessed deepest at the second portion ofthe first stress relaxation portion.
 9. The power semiconductor moduleaccording to claim 1, wherein the insulating substrate includes a firstinsulating substrate segment and a second insulating substrate segment,wherein the first conductive circuit pattern is provided on the firstinsulating substrate segment, the second conductive circuit pattern isprovided on the second insulating substrate segment, and the secondinsulating substrate segment is separated from the first insulatingsubstrate segment by a second gap, and in plan view of the first mainface, the first stress relaxation portion overlaps the second gap. 10.The power semiconductor module according to claim 9, further comprisinga base plate disposed on an opposite side from the first semiconductordevice and the second semiconductor device with respect to theinsulating substrate, wherein the first insulating substrate segment andthe second insulating substrate segment are joined to the base plate.11. The power semiconductor module according to claim 1, furthercomprising a second barrier layer such that the second barrier layer andthe first barrier layer are stacked.
 12. The power semiconductor moduleaccording to claim 4, further comprising a second barrier layer suchthat the second barrier layer and the first barrier layer are stacked,and in plan view of the first main face, at least a part of the firstthrough portion overlaps the second barrier layer.
 13. The powersemiconductor module according to claim 11, wherein at least one of thesecond barrier layer and the sealing member includes a second stressrelaxation portion.
 14. The power semiconductor module according toclaim 13, wherein the second barrier layer includes a third surface on aside where the first semiconductor device and the second semiconductordevice are located, and a fourth surface on a side opposite to the thirdsurface, and the second stress relaxation portion is a third recessformed in at least one of the third surface and the fourth surface. 15.The power semiconductor module according to claim 13, wherein the secondbarrier layer includes a third surface on a side where the firstsemiconductor device and the second semiconductor device are located,and a fourth surface on a side opposite to the third surface, and thesecond stress relaxation portion is a second through portion connectingthe third surface to the fourth surface.
 16. The power semiconductormodule according to claim 13, wherein in plan view of the first mainface, at least a part of the second stress relaxation portion overlapsthe first stress relaxation portion.
 17. A power conversion apparatuscomprising: a main conversion circuit including the power semiconductormodule according to claim 1, wherein the main conversion circuitconverts input power and outputs the converted power, and a controlcircuit to output a control signal to the main conversion circuit forcontrolling the main conversion circuit.
 18. The power semiconductormodule according to claim 12, wherein at least one of the second barrierlayer and the sealing member includes a second stress relaxationportion.